CN104506172B - A kind of 4 20mA current loop control PWM output circuits - Google Patents
A kind of 4 20mA current loop control PWM output circuits Download PDFInfo
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- CN104506172B CN104506172B CN201410697105.7A CN201410697105A CN104506172B CN 104506172 B CN104506172 B CN 104506172B CN 201410697105 A CN201410697105 A CN 201410697105A CN 104506172 B CN104506172 B CN 104506172B
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Abstract
The present invention relates to signal of communication conversion art, it discloses a kind of 4 20mA current loop control PWM output circuits, 4 20mA current ring communications are carried out I/V switching reliabilities are high, poor anti jamming capability being overcome, and the drawback such as complicated, cost height of I/F converting circuit structures.The circuit includes triangle wave generating circuit, I/V translation circuits and comparator；The input of the I/V translation circuits is connected with input current signal；The triangle wave generating circuit output signal is connected with comparator input terminal respectively with the output signal of I/V translation circuits.The present invention is applied to conversion process of the receiver front end to electric current ring signal.
Description
Technical field
The present invention relates to signal of communication conversion art, and in particular to a kind of 4-20mA current loop controls PWM output circuit.
Background technology
At present, there are many Process Control Systems in industry spot, from simple flow-control to complicated electrical network, from environment
Control system is to steel mill process control；These control systems are made up of such as CPU, input module, mould a lot of modules
Analog quantity is exported, digital output, power supply etc..Need between disparate modules into row data communication, wherein 4～20mA electric current loops lead to
Letter is because of its strong antijamming capability, long transmission distance, reliable and stable and be widely used.As receiver can not be directly to electric current loop
Signal is utilized, it usually needs electric current ring signal is transformed into frequency signal or voltage signal, i.e. I/F conversion, I/V conversion.
In current ring communication, the precision of I/V conversion is relevant with the precision of A/D converter, and voltage signal is easily disturbed, and receives
The impact of overall fabric swatch；And I/F translation circuits are complicated, and the passband for needing design wider, the demodulation of signal, filtering are proposed
Very high requirement.
Content of the invention
The technical problem to be solved is：A kind of 4-20mA current loop controls PWM output circuit is proposed, to overcome
Carry out to 4-20mA current ring communications that I/V switching reliabilities are high, poor anti jamming capability, and I/F converting circuit structures complicated, into
This high drawback.
The present invention solves the technical scheme that adopted of above-mentioned technical problem：
A kind of 4-20mA current loop controls PWM output circuit, including triangle wave generating circuit, I/V translation circuits and compares
Device；The input of the I/V translation circuits is connected with input current signal；The triangle wave generating circuit output signal and I/V
The output signal of translation circuit is connected with comparator input terminal respectively.
Further, also include output circuit, the comparator output signal is connected with output circuit.
Specifically, the triangle wave generating circuit include first resistor R416, second resistance R417,3rd resistor R418,
4th resistance R419, the 5th resistance R420, the 6th resistance R421, the 7th resistance R422, the fortune of the first capacitance C410 and first
Put U401A, the second amplifier U401B；First power Vcc is connected with the first amplifier U401A inverting input through first resistor R416；
The first amplifier U401A inverting input is connected to after second resistance R417 is in parallel with 3rd resistor R418；First amplifier U401A is defeated
Go out end to be connected with the 7th resistance R422；First amplifier U401A in-phase input end is gone here and there through the 4th resistance R419 and the 7th resistance R422
The first amplifier U401A outfan is connected to after connection；7th resistance R422 is connected the second amplifier with after the 6th resistance R421 series connection
U401B inverting inputs；Second amplifier U401B inverting input is through the first electric capacity C410 and the second amplifier U401B outfan phase
Even；Second amplifier U401B outfan is connected to the first amplifier U401A in-phase input end through the 5th resistance R420；Second amplifier
U401B in-phase input ends are connected with the first amplifier U401A inverting input.
Specifically, the I/V translation circuits include the 8th resistance R409, the 9th resistance R410, the tenth resistance R411, the tenth
One resistance R412, the 12nd resistance R413, the 13rd resistance R414, the 14th resistance R415, the second electric capacity C408, the 3rd electric capacity
C409 and the 3rd amplifier U401D；9th resistance R410 is connected in parallel on current signal input mouth two ends；Current input signal interface is just
End is connected with the 3rd amplifier U401D in-phase input end through the 8th resistance R409；Second source is through the fortune of the tenth resistance R411 and the 3rd
Put U401D in-phase input ends to be connected；3rd amplifier U401D in-phase input end is connected to ground through the second electric capacity C408；3rd amplifier
U401D inverting inputs are connected to ground through the 12nd resistance R413；Second source is through the 11st resistance R412 and the 3rd amplifier
U401D inverting inputs are connected；3rd amplifier U401D outfan is anti-phase defeated with the 3rd amplifier U401D through the 13rd resistance R414
Enter end to be connected；The filter circuit that the connection of 3rd amplifier U401D outfan is made up of the 14th resistance R415, the 3rd electric capacity C409.
Specifically, the comparator U401C inputs connect the second amplifier U401B outfan and the 14th resistance respectively
R415；The filter circuit that the connection of comparator U401C outfans is made up of the 15th resistance R423 and the 4th electric capacity C411.
Specifically, the output circuit includes optocoupler N201, the 16th resistance R208, the 17th resistance R209, the 5th electricity
Hold C212；Optocoupler N201 inputs export filtered signal with comparator U401C and are connected；Optocoupler N201 outfans and the 5th electricity
Hold C212 in parallel；Optocoupler N201 outputs terminate the 16th resistance R208, and optocoupler N201 outfans connect through the 17th resistance R209
It is connected to receiver.
The invention has the beneficial effects as follows：
1. 4-20mA electric current ring signals can be converted to pwm signal；
2. output pwm signal dutycycle and the linear corresponding relation of input current signal size；
3.PWM frequencies are fixed and adjustable；
4.PWM duty cycle ranges are adjustable；
5. circuit structure is simple, high precision；
6. highly reliable, workable.
Description of the drawings
Fig. 1 is 4-20mA current loop controls PWM output circuit structure block diagram of the present invention；
Fig. 2 is 4-20mA current loop controls PWM output circuit example structure figure of the present invention.
Specific embodiment
It is contemplated that a kind of 4-20mA current loop controls PWM output circuit is proposed, logical to 4-20mA electric current loops to overcome
Letter carries out that I/V switching reliabilities are high, poor anti jamming capability, and the drawback such as complicated, cost height of I/F converting circuit structures.Such as Fig. 1
Shown, which includes triangle wave generating circuit, I/V translation circuits and comparator；The input of the I/V translation circuits and input electricity
Stream signal is connected；The triangle wave generating circuit output signal is input into comparator respectively with the output signal of I/V translation circuits
End is connected.
Input current signal is changed into voltage signal by the I/V translation circuits；The triangle wave circuit is used for producing fixation
The triangular signal of frequency；The voltage signal is compared generation pwm signal with triangular signal by comparator；Described defeated
Go out circuit (optional) and reliability can be improved to pwm signal and the Phototube Coupling of main circuit.
Below in conjunction with the accompanying drawings and embodiment the solution of the present invention is further described：
As shown in Fig. 2 in 4-20mA current loop control PWM output circuits in this example,
The triangle wave generating circuit includes first resistor R416, second resistance R417,3rd resistor R418, the 4th resistance
R419, the 5th resistance R420, the 6th resistance R421, the 7th resistance R422, the first capacitance C410 and the first amplifier U401A,
Second amplifier U401B；Power Vcc is connected with the first amplifier U401A inverting input through first resistor R416；Second resistance R417
The first amplifier U401A inverting input is connected to after in parallel with 3rd resistor R418；First amplifier U401A outfan and the 7th electricity
Resistance R422 is connected；First amplifier U401A in-phase input end is connected to after connecting with the 7th resistance R422 through the 4th resistance R419
One amplifier U401A outfan；7th resistance R422 is connected the second amplifier U401B anti-phase input with after the 6th resistance R421 series connection
End；Second amplifier U401B inverting input is connected with the second amplifier U401B outfan through the first electric capacity C410；Second amplifier
U401B outfans are connected to the first amplifier U401A in-phase input end through the 5th resistance R420；Second amplifier U401B homophase input
End is connected with the first amplifier U401A inverting input.
The I/V translation circuits include the 8th resistance R409, the 9th resistance R410, the 11st resistance of the tenth resistance R411
R412, the 12nd resistance R413, the 13rd resistance R414, the 14th resistance R415, the second electric capacity C408, the 3rd electric capacity C409 and
3rd amplifier U401D；9th resistance R410 is connected in parallel on current signal input mouth two ends；Current input signal interface anode is through
Eight resistance R409 are connected with the 3rd amplifier U401D in-phase input end；Power supply is through the tenth resistance R411 and the 3rd amplifier U401D homophase
Input is connected；3rd amplifier U401D in-phase input end is connected to ground through the second electric capacity C408；3rd amplifier U401D is anti-phase defeated
Enter end and be connected to ground through the 12nd resistance R413；Power supply is through the 11st resistance R412 and the 3rd amplifier U401D inverting input phase
Even；3rd amplifier U401D outfan is connected with the 3rd amplifier U401D inverting input through the 13rd resistance R414；3rd amplifier
The filter circuit that the connection of U401D outfans is made up of the 14th resistance R415, the 3rd electric capacity C409.
The comparator U401C inputs connect the second amplifier U401B outfan and the 14th resistance R415 respectively；Relatively
The filter circuit that the connection of device U401C outfans is made up of the 15th resistance R423 and the 4th electric capacity C411.
The output circuit includes optocoupler N201, the 16th resistance R208, the 17th resistance R209, the 5th electric capacity C212；
Optocoupler N201 inputs export filtered signal with comparator U401C and are connected；Optocoupler N201 outfans and the 5th electric capacity C212
In parallel；Optocoupler N201 output the 16th resistance R208 of termination are connected to receiver through the 17th resistance R209.
The operation principle of examples detailed above circuit is：
When 4-20mA electric currents ring signal is input into through Current Input ports, through the electricity that the 9th resistance R410 is transformed to
Pressure signal Vin, the 3rd amplifier U401D and the 8th resistance R409, the tenth resistance R411, the 11st resistance R412, the 12nd resistance
Voltage signal is amplified by the amplifying circuit of R413, the 13rd resistance R414 composition, and amplifier output voltage is Triangle wave generating circuit frequency of oscillation
Oscillator center point voltage isThe current signal of amplification and triangular wave oscillation signal
Pwm signal is relatively produced, then through spacing output circuit output pwm signal.
Circuit in for examples detailed above can carry out following parameter setting：
1.PWM signal dutyfactor range set methods：The oscillator center point voltage and I/V of adjustment triangle wave generating circuit
The amplification of translation circuit.
2. the oscillator center point voltage of triangle wave generating circuit sets：Adjustment resistance first resistor R416, second resistance
R417,3rd resistor R418 resistance are set；
The amplification of 3.I/V translation circuits sets：Adjust the 8th resistance R409, the 9th resistance R410, the tenth resistance
R411, the 11st resistance R412, the 12nd resistance R413, the 13rd resistance R414 values.
4.PWM signal frequency establishing methods：Adjust the 4th resistance R419, the 5th resistance R420, the 6th resistance R421 and
One electric capacity C410 values are set.
5. current signal is set with output pwm signal dependency：The signal of comparator input terminal is exchanged, output can be set
Pwm signal is positive correlation or negative correlation.
The preferred embodiments of the present invention are the foregoing is only, the present invention is not limited to, for the skill of this area
For art personnel, the present invention can have various modifications and variations.All made within the spirit and principles in the present invention any repair
Change, equivalent, improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1. a kind of 4-20mA current loop controls PWM output circuit, it is characterised in that including triangle wave generating circuit, I/V conversion electricity
Road, output circuit and comparator；The input of the I/V translation circuits is connected with input current signal；The triangular wave occurs
Circuit output signal is connected with comparator input terminal respectively with the output signal of I/V translation circuits, the comparator output signal
It is connected with output circuit；The triangle wave generating circuit includes first resistor (R416), second resistance (R417), 3rd resistor
(R418), the 4th resistance (R419), the 5th resistance (R420), the 6th resistance (R421), the 7th resistance (R422), the first electric capacity electricity
Hold (C410) and the first amplifier (U401A), the second amplifier (U401B)；First power supply (Vcc) is through first resistor (R416) and first
Amplifier (U401A) inverting input is connected；The first amplifier is connected to after second resistance (R417) is in parallel with 3rd resistor (R418)
(U401A) inverting input；First amplifier (U401A) outfan is connected with the 7th resistance (R422)；First amplifier (U401A) is same
Phase input is connected to the first amplifier (U401A) outfan after connecting with the 7th resistance (R422) through the 4th resistance (R419)；The
Seven resistance (R422) are connected the second amplifier (U401B) inverting input with after the series connection of the 6th resistance (R421)；Second amplifier
(U401B) inverting input is connected with the second amplifier (U401B) outfan through the first electric capacity (C410)；Second amplifier (U401B)
Outfan is connected to the first amplifier (U401A) in-phase input end through the 5th resistance (R420)；Second amplifier (U401B) homophase input
End is connected with the first amplifier (U401A) inverting input；
The I/V translation circuits include the 8th resistance (R409), the 9th resistance (R410), the tenth resistance (R411), the 11st electricity
Resistance (R412), the 12nd resistance (R413), the 13rd resistance (R414), the 14th resistance (R415), the second electric capacity (C408), the
Three electric capacity (C409) and the 3rd amplifier (U401D)；9th resistance (R410) is connected in parallel on current signal input mouth two ends；Electric current is defeated
Enter signaling interface anode to be connected with the 3rd amplifier (U401D) in-phase input end through the 8th resistance (R409)；Second source is through the tenth
Resistance (R411) is connected with the 3rd amplifier (U401D) in-phase input end；3rd amplifier (U401D) in-phase input end is through the second electric capacity
(C408) it is connected to ground；3rd amplifier (U401D) inverting input is connected to ground through the 12nd resistance (R413)；Second source is passed through
11st resistance (R412) is connected with the 3rd amplifier (U401D) inverting input；3rd amplifier (U401D) outfan is through the 13rd
Resistance (R414) is connected with the 3rd amplifier (U401D) inverting input；The connection of 3rd amplifier (U401D) outfan is by the 14th electricity
The filter circuit that resistance (R415), the 3rd electric capacity (C409) are constituted.
2. a kind of 4-20mA current loop controls PWM output circuit as claimed in claim 1, it is characterised in that the comparator
(U401C) input connects the second amplifier (U401B) outfan and the 14th resistance (R415) respectively；Comparator (U401C) is defeated
Go out the filter circuit that end connection is made up of the 15th resistance (R423) and the 4th electric capacity (C411).
3. a kind of 4-20mA current loop controls PWM output circuit as claimed in claim 2, it is characterised in that the output electricity
Road includes optocoupler (N201), the 16th resistance (R208), the 17th resistance (R209), the 5th electric capacity (C212)；Optocoupler (N201)
Input exports filtered signal with comparator (U401C) and is connected；Optocoupler (N201) outfan and the 5th electric capacity (C212) and
Connection；Optocoupler (N201) output terminates the 16th resistance (R208), and optocoupler (N201) outfan connects through the 17th resistance (R209)
It is connected to receiver.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201410697105.7A CN104506172B (en) | 2014-11-26 | 2014-11-26 | A kind of 4 20mA current loop control PWM output circuits |
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| CN201410697105.7A CN104506172B (en) | 2014-11-26 | 2014-11-26 | A kind of 4 20mA current loop control PWM output circuits |
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| CN104506172A CN104506172A (en) | 2015-04-08 |
| CN104506172B true CN104506172B (en) | 2017-03-15 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106357169A (en) * | 2016-10-20 | 2017-01-25 | 珠海格力节能环保制冷技术研究中心有限公司 | PWM modulation circuit and direct-current brushless motor controller |
| CN107120303A (en) * | 2017-07-13 | 2017-09-01 | 迈普通信技术股份有限公司 | Circuit for controlling speed of fan and communication equipment |
| CN108414825A (en) * | 2018-02-07 | 2018-08-17 | 大连理工大学 | A kind of input and output scaling method of 4-20mA electric current loops |
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| KR101677728B1 (en) * | 2009-10-26 | 2016-11-21 | 페어차일드코리아반도체 주식회사 | Power factor correction circuit and driving method thereof |
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| CN1363916A (en) * | 2001-01-05 | 2002-08-14 | Lg电子株式会社 | Drive circuit for displaying active matrix method in device |
| US7035835B2 (en) * | 2003-06-12 | 2006-04-25 | Winbond Electronics Corporation | High-precision current-mode pulse-width-modulation circuit |
| CN101738530A (en) * | 2009-12-04 | 2010-06-16 | 合肥荣事达三洋电器股份有限公司 | Electrolytic current detection circuit of variable-frequency washing machine |
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Effective date of registration: 20220119 Address after: 621000, No. 35 Mian Xing Dong Road, hi tech Zone, Sichuan, Mianyang Patentee after: SICHUAN CHANGHONG PRECISION ELECTRONIC TECHNOLOGY Co.,Ltd. Address before: 628017 Sichuan Changhong Xinrui Technology Co., Ltd., wangjiaying urban industrial park, Guangyuan Economic Development Zone, Sichuan Province Patentee before: SICHUAN CHANGHONG-SINEW TECHNOLOGY Co.,Ltd. |